We identify a transient enhancement of the depolarizing field, leading to an unexpected quench of net polarization, during the growth of a prototypical metal-ferroelectric-metal epitaxial system made of BaTiO 3 and SrRuO 3 . Reduced conductivity and, hence, charge screening efficiency in the early growth stage of the SrRuO 3 top electrode promotes a breakdown of ferroelectric BaTiO 3 into domains. We demonstrate how a thermal annealing procedure can recover the single-domain state. By tracking the polarization state in situ, using optical second harmonic generation, we bring new understanding to interface-related electrostatic effects in ferroelectric capacitors.

K 8 K. We thus observe a scenario of quasiparticle

Difference frequency generation quantum cascade lasers are well-suited for applications requiring narrow-linewidth emitters.

We measure the quasiparticle weight in the heavy-fermion compound CeCu6−xAux (x = 0, 0.1) by time-resolved terahertz spectroscopy for temperatures from 2 up to 300 K. This method distinguishes contributions from the heavy Kondo band and from the crystal-electric-field satellite bands by different terahertz response delay times. We find that the formation of heavy bands is controlled by an exponentially enhanced, high-energy Kondo scale once the crystal-electric-field states become thermally occupied. We corroborate these observations by temperature-dependent dynamical meanfield calculations for the multiorbital Anderson lattice model and discuss consequences for quantumcritical scenarios.arXiv:1810.07412v2 [cond-mat.str-el]

Erbium doped low symmetry Y2SiO5 crystals attract a lot of attention in perspective of quantum information applications. However, only doping of the samples during growth is available up to now, which yields a quite homogeneous doping density. In the present work, we deposit Er 3+ -ions by the focused ion beam technique at Yttrium sites with several fluences in one sample. With a photoluminescence study of these locally doped Er 3+ :Y2SiO5 crystals, we are able to evaluate the efficiency of the implantation process and develop it for the highest efficiency possible. We observe the dependence of the ion activation after the post-implantation annealing on the fluence value.Keywords: rare earth, concentration dependance, annealing, activation Rare-earth (RE) doped materials are in the focus of interest for modern physics due to their specific properties, such as the presence of high coherence transitions inside the 4f shell and long optical and microwave coherence times. The rapid progress with the REs has been expressed in number of dramatic achievements: the demonstration of long living optical holes in europium-doped yttrium silicate Among other REs, the erbium doped crystals are outstanding due to the presence of optical transitions inside the telecom C-band at the wavelength of around 1530-1565 nm. Moreover, the Er 3+ :Y 2 SiO 5 (Er:YSO) crystal possesses the longest measured optical coherence time of about 6 ms among all other solid state systems [5,6]. On the hand of the magnetic properties, erbium ions possess a very large magnetic moment of 7µ B . Electron Spin Resonance (ESR) studies revealed that the T 2 coherence time can reach the huge value of 100 ms [7]. The development of high fidelity and long-life quantum memory will boost the implementation of long distance quantum communication protocols in already existing fiber optical networks [8,9].So far, all of these research deals with the doped-asgrown Er 3+ :Y 2 SiO 5 crystals. However, implementation of Focused Ion Beam (FIB) technique for doping of the YSO crystals looks as a rather handy possibility to perform different types of quantum elements and quantum gates on one chip without mask-and alignment processes. It is especially advantageous in circuit Quantum Electrodynamics (QED) implementations, where one wants to separate the memory elements from the computation elements on the chip. FIB possesses a wide range of flexible parameters, which allow to perform implantation with controlled fluences at different depths at selected positions. Proper adjustment of these implantation parameters, as well as annealing procedure, makes it possible to implant the Erbium ions in the Yttrium sites and recover the distorted site-symmetry. In this letter, we discuss the results of FIB implantation of the Y 2 SiO 5 crystals with the Erbium ions.The implantation was performed into a nominally undoped YSO crystal, supplied by the Scientific Materials Inc. Doped as-grown Er:YSO 0.005 % crystal was taken as reference. All the crystals have the same orientation of opt...

Two-dimensional spectroscopy is performed on a terahertz (THz) frequency quantum cascade laser (QCL) with two broadband THz pulses. Gain switching is used to amplify the first THz pulse and the second THz pulse is used to probe the system. Fourier transforms are taken with respect to the delay time between the two THz pulses and the sampling time of the THz probe pulse. The two-dimensional spectrum consists of three peaks at (ω = 0, ω = ω), (ω = ω, ω = ω), and (ω = 2ω, ω = ω) where ω denotes the lasing frequency. The peak at ω = 0 represents the response of the probe to the zero-frequency (rectified) component of the instantaneous intensity and can be used to measure the gain recovery.

No abstract

This paper presents experimental results that characterize implanted layers in silicon being the result of a high energy implantation of O ?6 ions. We propose a simple relation between attenuation of photothermal radiometry and/ or modulated free carrier absorption amplitudes, the implanted layer thickness and its optical absorption coefficient. The thickness of the implanted layers was determined from capacitance-voltage characteristics and computations with the TRIM program. The obtained results allowed to estimate changes of the optical absorption coefficient of the oxygen implanted layers indicating the amorfization of the layers.